Commercially available automated equipment currently exists for analyzing the particulate or cell concentration in blood. This equipment measures either the interaction of the blood particles with electric fields or the interaction of the blood particles with visible radiation. Instruments which utilize electric fields for blood analysis require rather complex equipment while instruments utilizing optical analysis techniques are simpler. However, the simplicity found with optical instruments is frequently obtained at the expense of accuracy.
A disadvantage of utilizing optical equipment to analyze the particulate concentration in blood is the fact that the visible radiation intensity used to determine particulate concentration does not vary linearly with changes in particulate concentration. This is due to the fact that instruments using nephelometric and/or turbinometric phenomenon have non-linear characteristics as a result of random scattering of light. The non-linear response of the optical equipment to the particulate concentration makes the interpretation of the output data difficult and somewhat inaccurate. If instrumentation is added to the optical equipment to linearize its response, its complexity rapidly approaches that of the electric field instruments. Thus, a highly desirable goal in blood analysis is to develop a simple optical instrument not requiring elaborate instrumentation, which responds linearly to changes in particulate concentration.
Moreover, in the past it has been necessary, when conducting these types of tests to separately mix the required test reagents with the test sample, thereby substantially increasing both the time necessary to complete the test and the chance of contaminating the sample. In order to overcome these shortcomings, attempts have been made to produce a test strip or vessel impregnated with the actual test reagents. However, these products have proved unsatisfactory for a number of reasons. The first is that in many cases it has been difficult, if not impossible, to adapt the vessel and/or strip material to absorb and hold, in a stable condition, the necessary test reagents, dyes, or enzymes. Secondly, due to the type of dyes either used or generated, as well as the fact that these dyes are not molecularly bonded to the vessel or strip material, they do not result in a stable and permanent color. Rather, these tests must be read during a relatively short period of time after the test reaction is complete.
It is therefore an object of this invention to provide simple optical equipment for automatically analyzing the particulate content in blood bearing solutions.
It is another object of this invention to provide optical equipment capable of simultaneously analyzing and detecting two constituents in blood bearing solutions.
It is a further object of this invention to provide an instrument capable of obtaining a linear reading of the degree of agglutination of red blood cells.
A still further object of this invention is to provide a technique for increasing the linearity of response of optical equipment used to determine the particulate concentration in whole blood and in other solutions.
A further object of this invention is to provide a vessel adapted to absorb a number of various test reagents and enzymes which will be leached out when the test sample is added thereto.
Another object of this invention is to provide a test strip impregnated with various test reagents adapted to indicate specific analyte concentration by means of changes in color.
Still, a further object of this invention is to provide a test strip which will produce a permanent record of test results.
Still, other objects and advantages of the present invention will be obvious and in part be apparent from the specification and attached drawings